Device for the automatic detection of genuine coins



June 30, 1942. .1. F. MULLEN ETAL 2,288,014

DEVICE FOR THE AUTOMATIC PETECTION OF GENUINE COINS Filed Jan. 12, 19403 Sheets-Sheet l June 30, 1942. l J. F. MULLEN ETAL DEVICE FOR THEAUTOMATIC DETECTION OF GENUINE COINS 3 SheetS Sheet 2 Filed Jan. 12,1940 I NVE N TORY c/Zmes F/kd/exr Wnd F growls ATToR Yi June 3 1941 AL2,283,014

DEVICE FOR THE AUTOMATIC DETECTION OF GENUINE COINS Filed Jan. 12, 1940s Sheets-Sheet s Many very clever and ingenious coin a slug of a basermetal I a great other than one of Patented June 30, 1942 navrcii sonJames F. Mullen, Rive Dearborn, Mi

Brooks,

THE AUTOMATlC DETECTION OF GENUINE COINS r Rouge, and Wendell B.

ch., assignors to Electric SlugBeiector and Manufacturing Corporation, acorporation of Missouri Application January 12, 1940, Serial No. 313,550

4 Claims.

This invention relates to improvements in that type of devices which isadapted. to be used in connection with various types of automatic coinoperated machines and employed for the auto-- matic detection andrejection of slugs of baser' metals than the coin by which the machineis intended to be actuated While it has been found that slugs having thesame dimensions as a genuine coin, but constructed of baser metals, canbe very readily detected by the use of thermo-electric orelectro-chemical means for contact with the slug upon its insertion inthe device, and although many attempts have been made to deviseautomatic coin detectors of this general type, as far as we are aware,none oi these devices that have been heretofore suggested have beenentirely successful.

expedients are resorted to by the type of people whom we will designategenerally as the unscrupulous to beat" coin actuated machines. One ofthe common expedients in the slot of a coin controlled machine which iscapable of actuating erly and. to insert immediately after the genuinewhich, iollowing immediately after the genuine coin, will result in adouble actuation of the machine because of the lag in thethermo-electric or electro-chemv ical detecting mechanism.

As far as we are aware, no one has heretofore made available a coindetecting device capable present invention;

is that of inserting a genuine coin the electrical device prop- Ipanying drawings forming a part hereof and wherein:

Fig. l is a diagrammatic view in section showing. the coin chute of acoin detector with a diagram of the electrical circuits associatedtherewith; Fig. la is a diagrammatic view indicating the manner in whicha relay may be connected in an electrical circuit of the coin detectorfor completing a circuit to a main machine; Fig. 2 is a side elevationof a coin detecting device constructed in accordance withthe principlesof the Fig. 3 is a vertical cross-sectional view through the coin chuteof the device shown in Fig. 2; Fig. 4 is a rear view of the device withthe casing partly removed; Fig. 5 is a side view of the lower portion ofthe structure shown in Fig. 4 as seen from the right hand side thereof;Fig. 6 is a section along the line 6-6 of Fig. 5; Fig. '7 is afragmentary cross section taken on the line 1-1 of Fig. 2; Fig. 8 is IOtrode is connected by a wire 20a with a galvanometer type relay switch23, while the elecof operating with sufilcient accuracy to safeguard theoperation of the main machine against all of the more commonexpedientsemployed by the unscrupulous. Consequently, none of the coindetecting devices heretofore proposed have ever gone into general use,although there has been demand for devices of this character andalthough the losses resulting .from the improper practices of theunscrupulous reach in the aggregate to quite considerable sums of money.

One of the principal objects of this invention, therefore, is to providea coin detecting device in which there will beassociated, incombination, means for preventing the-actuation of a main machine by aspurious coin. I

It will be understood that throughout the foltrode 2| is similarlyconnected to said galvanom eter by means of a wire 21a.

In the form shown in Fig. l the electrode 20 8 is adapted to be heatedby a heating coil 36 connected directly to a main source of either A. C.

or.D. C. electricity by means of connecting wires 366, Nb. Whena coin isinserted into the coin slot of the coin chute 22, it will, if the coinis 40 of the proper diameter, make contact with the lowing descriptionwe will employ the term I the connecting wires 20a and 2m and thegelspurious coin electrodes 20, 2| and due to the fact that theelectrode 20 is heated while the electrode 2! is cold, athermoelectrical eflect will be produced in accordance with thewell-known characteristics of devices of this character, causing anelectromotive force of small magnitude to b'e'generated in what may betermed the primary actuatingcircuit of the device, this circuitconsisting of the electrodes 20, 2|, the inserted coin,

vanometer type relay 23.

The galvanometer 23 is of standard construction, including agalvanometer needle 32, which carries a movable switch contact 33adapted, upon acertain amount of deflection oi the nee- .cuit will bereferred to as the dle 32, to make contact with a fixed contact 34. Theneedle 32 may be so adjusted that it will be deflected an amount justsufficient to cause the contacts 33 and 34 to be closed only when agenuine coin is in contact with the electrodes 20, 2|.

Due to the fact that galvanometer types of switches, sufllcientlysensitive to react to the presence of a-minute el-ectromotive force suchas is induced in the actuating circuit of the device, are of necessityvery light and delicate mechanisms, the use of a galvanometer switch tocarry the full load of the main electrical circuit of the device hasproven to be one of the serious causes of difficulty with the accuracyof coin detecting devices as heretofore constructed due to arcing,pitting and sticking of the galvanometer switch contacts. Thereforemeans are incorporated in the present invention to employ thegalvanometer switch only momentarily and to relieve such switch of thenecessity for carrying the larger currents employed for actuating thecoin detector. I

The needle 32 of the galvanometer is connected by a connector 3211 toone terminal of thecoil of a solenoid 39 while the other terminal ofsaid coil is connected by a connector 39a to the main line 36a at somesuitable point, such as-indicated at 35; a pair of switch contacts 31,38' being interposed in the connector 390 for a purpose presently to bedescribed. The fixed contact 34 of the galvanometer switch is connectedby a conductor 34a to the main line 36b at any suitable point 42, sothat when the switch contacts 33, 34 are closed, current from the mainsource of electricity is established to the solenoid 39 through acircuit consisting of the connector 390, the connector 32a, galvanometercontacts 33, 34 and the connectors 34a. This cirsecondary actuatingcircuit of the device.

The solenoid 39 is provided with a movable core 43 in accordance withthe usual construction of such devices.

In order to relieve the galvanometer' switch contacts of carrying theentire load and to avoid objectionable pitting and arcing of the switchcontacts 33, 34, the solenoid core' 43 has associated with it a pair ofswitch contacts 48, 49;

the manner in which such switch contacts are mechanically associatedwith the solenoid core 43 being shown in Fig. 6 of the drawings.

Mounted in insulating material below the solenoid 39 there is a pair ofspring conductors l6 and 11 upon which the contacts 48 and 49 aremounted. A plunger consisting of a shaft 18 and a head 19 is attached tothe movable core 43 of the solenoid so that the shaft portion 18projects through holes provided in the spring conductors I5 and 11.Hence, when the solenoid 39 is energized, the core 43 will be caused tomove to the left from its position shown in Fig. 6, carrying the plungerwith it, so that the head 19 of the plunger will engage the springconduc tor l1 and bend it to the left toward the spring conductor 16.This movement will result in the completion of an electrical circuitacross the con- 7 tacts 48 and 49, which circuit will be maintained aslong as the solenoid 39 remains energized. As.

soon as the solenoid is de-energized, the force holding the core 43 tothe left of its position of Fig. 5 will no longer exist, whereupon thespring conductor 11 will resume its normal position by reason of itsinherent resiliency, thus breaking the circuit across the contacts 48and 49 and also returning the core 43 to the position shown in Fig. 6.

By reference to Fig. 1 it will be seen that the switch contacts 48, 49are arranged in a shunt circuit connected across the conductors 32a, 340between points 46 and 41 thereon by wires 49a and 48a respectively, sothat when the switch contacts 48, 49 are closed upon the energization ofthe solenoid 39 by the closing of the secondary actuating circuit,current from the main source of electricity flowing to the solenoid coil39 will be shunted, or by-passed, around the galvanometer 23 and itsswitch contacts 33, 34, through the shunt circuit which includes theswitchcontacts 48, 49. The circuit so formed, extending from the mainline 360 through the conductor 39a, the solenoid 39, the conductor 32ato point 46 thereon, the conductor 49a, switch contacts 49 and 48,conductors 48c and 34a to the main line 36b, will hereafter be referredto l as the work circuit of the device.

As will be seen by reference to the diagrammatic showing of Fig. 1 ofthedrawings-and also by reference to Figs. .2 and 3, the coinchute 22adjacent to its lower. end is provided with a pair of branch chutes, oroutlets, 44 and 45, the branch chute 45 leading to a coin box (notshown) for retention of the genuine coins, while the branch 44 is arejector chute through which the spurious coins are deflected to preventactuation of the main machine by such spurious coins. The branching ofthe coin chute to form the delivery branches 44, 45 is arrangedso thatthe entrance to the rejector chute 44 is immediately below, and invertical alignment with, the main coin chute 22, in order that a coininserted in the main chute'22 will normally fall by gravitydirectly intothe branch chute 44. The entrance to the'branchchute 45 which leads tothe coinbox is in effect formed in the vertical side wall of the chute22; and, as clearly indicated in the drawings, the location of thesolenoid 39 tranceto the branch chute 44 "so es to obstruct thisentrance. When the core 4 3 is caused to be projected into the coinchute through the energization of the solenoid, the coin dropped intothe chute 22 will strike the end of the core 43 and will be deflectedlaterally into the genuine coin chute 45 to be delivered thereby to acoin box.

Located adjacent the exit of the branch coin chute 45 is a normallyclosed cut-off switch comprising -a .pair of switch contacts 40, 4| andshown=diagrammatically in Fig. 1 as interposed in the connector 34abetween the points 41 and 42 thereof. The actual construction 'of .thisswitch is shown best in Fig. 7, and it consistsof a fixed contact 4| anda movable contact 48 mounted on the lower end of a leaf spring 48a,

the spring 40a being adapted-to hold the mov- 50 so arranged that agenuine coin traveling through the coin chute 45 will pass between thecam surface 50 and the opposed wall of the chute 45 causing the block 5|to be moved outwardly of the chute against the action of the spring 49aso as to break the circuit between the contacts 48, 4|, and thusinterrupt the passage of current through the work circuit to thesolenoid 39. The

so as to establish a primary actuating circuit, cult which, in additionto the electrodes 28 and and then without releasing the coin to permit26 and the coin 24, consists of wires 29 and 20 it to travel into thecoin chute, to withdraw it leading to a galvanometer relay 3|. Thus theac- Means for preventing this is incorporated in from the coin slot.type of fraudulent operation the circuit of the solenoid 39 and consistsof having a pair of spring contacts 21, 32; the spring contact 38 beinga fixed one and the contact 31 a movable contact mounted at one end of aresilient arm pivoted intermediate its ends and having a spring 1iassociated with it for the purpose of normally holding the movablecontact 31 in engagement with the fixed contact 38. The resilient arm10, as shown in the'diagrammatic view of Fig. l, is arranged closelyadjacent'to the electrodes 20, 2| at the entrance to the coin chute, soas to project across the chute at one side thereof and to be spaced fromthe other side of the chute a distance slightly less than the diameterof the coin for which the chute is designed. As a result of thisconstruction, when a coin of the proper diameter is inserted into thecoin chute one side of the coin will engage the free end of the arm 10.As the coin is pushed past the free end of the arm 10 the arm will beflexed slightly to permit the coins passage and will also tend to bemoved in a counter-clockwise direction so as to press the contactmembers 31 and 38 into tighter contacting engagement. After the coin hasbeen inserted into the coin chute far enough to produce contact betweenthe electrodes 20, 2|, if an attempt should then be made to withdraw thecoin,

the free end of the arm 10 and move the-same in a clockwise directionagainst the action of the spring Ii to break the contact between themembers 31 and 38, thus interrupting the flow of ourrent to thesolenoid.

to actuate the.

v ance wire is provided.

the coin on being pulled outwardly from the coin chute will again engagetuation of the secondary actuating circuit connected through thisgalvanometer is produced in substantially the same mannerr-ashereinbefore described in connection with the thermo-electric type ofprimary actuating circuit.

As shown in Fig. 9 a variant form of thermoelectric primary actuatingcircuit is. employed which is designed to eliminate the necessity forthe continuous operation 0! the heating coil 36 which has previouslybeen described. In the modified form shown in Fig. 9 a connector havinga coin contacting loop 52 of high resist- The loop 52' projects into thecoin chute so as to contact a coin, indicated diagrammatically at 53,the inherent flexibility of the wire being employed for maintaining thecontacts of switch 54 normally out of engage ment. When the coin isinserted into the coin chute between the loop 52 and a cold electrodei2l, the pressure of the coin against the loop 52 will cause the switch54 to be closed. An instantaneous heating of the loop 52 will thenresult, due to its high resistance; The electromo-- tive force therebyproduced then flows through the circuit including'wires 51a and 520leading to a galvanometer 56. A choke coil 55 is preferably provided inthis actuating circuit of the relay to insure that only thethermo-electrically induced electromotive force reaches thegalvanometer.

While we are aware that the use of thermal electric effects to operate arelay and in turn a solenoid operated coin detector have heretofore typerelay provided pair of spaced coin contacts in said circuit adapted whenbridged by a genuine coin,*to cause said been suggested, we make noclaim broadly to such elements in combination but claim our improvementsin devices of this type. as follows.

J We claimr 1. In a coin detecting device, a primary actu-- atingcontrol circuit including a galvanometer with a pair of contacts, a

j relay to be energized, a coin selector including a.

coin chute, and a secondary actuating circuit for actuatihg sa'idselector including a solenoid, con- *nections thereto from a main sourceof elec- We have found, after extensive experimentation, that theeiiiciency of the thermo-electric primary actuating circuits of coindetecting devices depends very largelyupon the material used for thecoin detecting electrodes, and that nichrome and copper are preferablefor the hot and cold electrodes, respectively, with the hot electrodebeing maintained at a temperature of about 500 F. For silver coins theelectro-chemical type of primary actuating circuit as showndiagrammatically in Fig. 8 is preferably employed, in which case byanalogy to the thermoelectric circuit of Fig. 1, an electrode 25corresponds to the electrode 20 while in place of the hot electrode 24 awick 26 is immersed in an electrolyte 21 and is urged into contact withthe coin 24 by action of a suitable spring 28. When a coin 24 isinserted into the chute so as to contact with the electrodes 25 and 26,a primary actuating circuit is completed, and by the combination of thesilver coin and the electrolyte (which is acetic acid) in this circuit,electrochemical eiiects are produced resulting in the generation of anelectro-motive force in this cirtricity through said relay and a-workcircuit in shunt with said relay contacts having a normal- 1y openswitch therein mounted adjacent to said solenoid and coin selector to beclosed by said solenoid immediately said solenoid is caused to beactuated by the presence of a genuine coin in said primary circuit,thereby to maintain current through said work circuit around saidgaivanometer contacts directly to said solenoid from said main source ofelectricity, a normally closed switch in said work circuit and meansprojecting into said coin chute beyond said coin selector to cause saidnormally closed switch to be opened by the passage of a genuine coinafter said coin has passed said selector, thereby to interrupt the flowof current to said solenoid.

2. In a coin detecting device, a primary actuating control circuitincluding a galvanometer type relay provided with a pair of contacts, apair of spaced coin contacts in said circuit adapted when bridged by agenuine coin, to cause said relay to be energized, a coin selectorincluding a coin chute, and a secondary actuating circuit for actuatingsaid selector including a solenoid, connections thereto from a mainsource of electricitythroughsaid relay and a work circuit.

device is thereby ie-energized so that it is ready to receive the nextcoin.

As coin detecting devices of the. type herein disclosed are generallyused for the actuation of what we have termed a main machine, which inturn is electrically operated, we have indicated in Fig. la the mannerin which such a main machine may be actuated upon the insertion of agenuine coin in the coin detecting device. The means employed forthispurpose, as shown in Fig. la, consists of a solenoid switch 13interposed in the connector 34a between the points 14-15 so that whencurrent passes through the connector 24:: the solenoid 13 will close theswitch 80 in the electrical circuit 8| supplying power to the mainmachine.

The manner in which the parts, as heretofore described, operate is asfollows: When a coin is inserted in the coin slot at the entrance of themain coin chute 22 it bridges across the electrodes 20, 2 I, theelectrode 2| being normally held by the action of a spring 51 at adistance from the electrode 20 slightly less than the diameter of agenuine coin of the type by which the ma-' chine is intended to beoperated, and the electrode 20 being heated-by the coil 36 while theelectrode 2| remains unheated. The thermoelectric effects will cause anelectromotive force to be induced in the primary actuating circuit.

- If the coin is of the proper metallic composition of a genuine coin,the electromotive force so generated will cause the galvanometer needle32 to be moved the requisite distance to closethe contacts 33-, I4 andcurrent will then flow in the secondary actuating circuit from the mainline 36a through the connector 39a, through the coil of the solenoid 39,connectors 32a, switch contacts 83, 34 and connector 34a to the othermain line 36b, the switches 31, 38 and 40, 4| being normally closed. Ifthe coin that was inserted is a genuine coin, the actuation of thesolenoid 39 causes the solenoid core 43 to be projected into the coinwill not be projected into the coin chute; therefore, the coin will dropby gravity immediately into the rejector branch chute 44.

One of the more common expedients adopted by the unscrupulous to defrauda coin operated machine where such machine is protected by a coindetector is to insert first a genuine coin immediately followed by aspurious one, thereby to take advantage of the lag of theelectricallyoperated coin detectors heretofore employed.

The detector of the present invention has incorporated in itsconstruction means for effectively preventing this type of pettylarceny, which, of course, is only efiective against a main machinewhich is actuated by the coin after the same has passed through thedetecting device, and is not effective where the main machine isactuated by the actuation of the detecting device in the mannerdescribed herein and shown in Fig. 1a. This means consists of a novelarrangement and careful positioning of the solenoid actuated coindetector with respect to the cut-out switch 40, 4|.

As can be seen from an inspection of the showing of Fig. 2, the block5|, which causes the contacts 40 and 4| of the cut-ofi switch to beseparated upon the passage of a coin through the branch coin chute 45,is placed a very short distance from the junction of the branch coinchute 45 and the main coin chute 22 so that two coins cannot besimultaneously contained within the coin chute 45 with the deviceremaining actuated. Theoretically, at least, this means that chute 22 atthe entrance of the branch chute. 44, 7

thus causing the genuine coin to be deflected into thebranch chute"leading to the coin box.

The instant the current flows in the secondary actuating circuit toproduce an actuation of the solenoid 39, the switch 48, 49 in the workcircuit will be closed immediately, thus causing the current from themain line to be shunted'around the l J galvanometer 23 throughthe workcircuit, immediately relieving the galvanometer from performing anyfurther function until the primary actuating circuit is again closed bythe insertion of another genuine coin, and providing for the continuousenergization of the device from a steady source of supply rather thanrelying upon the small current momentarily induced in the pri- -maryactuating circuit forthis purpose, thereby,

.insuring the retention'of the genuine coin by the the distance betweenthe center of the solenoid core .43, and that point along the cam face50 of the block 5| at which a passing coin causes sufiicientdisplacement of the block 5| to break the circuit across the contacts 40and 4|, must be less than one and one-half times the diameter of thecoins being tested. r

. a This distance is designated as theoretical because other factorspresent in the operation of the device of the present invention make itpractically impossible. for one successively inserted coins to followanother so closely that their edges would contact. Due to the fact thatthe electrode 2| is ,spring held and as the contacting faces of both theelectrodes 20, 2| are either wedge-shaped or conical, thespringpressureof the electrodes against an entering coin tends to retard the passageof the coin somewhat until it has been pushed into the'coin slot farenough to bring the full diameter of the coin across and in contact withthe electrodes at which time the wedgeshape of the electrodes and thespring pressure device. As the geneuine coin passes through the V Ibranch chute 4? it engages the inclined cam surface 50 and moves theblock 5| against the action of the spring 40a to break the contactbetween the switch contacts 40,- thus cutting of! the work circuit tothe solenoid. The solenoid core 43 will therefore be withdrawn from thecoin chute and contactbetween the switch contacts 48, 49 is then broken.If the coin inserted in the coin chute is spurious rather than genuine,the

' electromotive force generated in the primary actuating circuit willnot be sufficient to close the galvanometer switch contacts 33, 34.Hence the secondary actuating circuit will not be closed, the solenoid39 will not be actuated and the core 43 tends to give the coin a markedacceleration into the coin chute. In other words, while the passage ofone coin through the device is being accelerated, the passage of afollowing coin is being retarded; and therefore, if a genuine coin isfirst inserted into the coin slot, its passage along the coin chute 22to the solenoid core 43 and thence to the cut-out switch 40, 4| is boundto occur before an immediately following spurious .coin can be insertedpast the electrodes .and travel the distance along the coin chute to thelocation of the solenoid core. Therefore, the passage of the firstgenuine coin will cause a deenergization of the device before afollowing coin, whether genuine or spurious, can reach the solenoid,core and be retained; and as a result, the following coin will berejected.

Another expedient frequently'employed to defraud coin operated machinesis to insert a genu ine coin far enough into the coin slot to producecontact thereof with the coin detecting electrodes closed switch to beopened by genuine coin past said selector,

aasaou in shunt with said relay contacts having a norreally open switchtherein mounted adjacent to said solenoid and coin selector to be closedby said solenoid immediately said solenoid is caused to be actuated bythe presence a genuine coin in said primary circuit, thereby to maintaincur rent through said vanometer contacts directly to said solenoid fromsaid main source of electricity, a normally closed switch in said workcircuit and means for actuating the same projecting into said coin chutebeyond said coin selector for causing said normally the passage of asaid means being spaced from said coin selector a distance relative tothe diameter of a genuine which 'the'device is designed that theinterruption oi current to said solenoid will be insured by the passageof a genuine coin past said selector before a second coin can travel insaid coin chute past said selector.

3. In a coin detecting device, a primary actuating control circuitincluding a galvanometer type relay provided with a pair of contacts, apair of spaced coin contacts in said circuit adapted when bridged by agenuine coin, to cause said relay to be energized, a coin selectorincluding a coin chute, and a secondary actuating circuit for actuatingsaid selector including a solenoid, connections thereto from a mainsource of electricity through said relay and a work circuit in shuntwith said relay contacts having a normally open switch therein mountedadjacent to said solenoid and coin selector to be closed by saidsolenoid immediately said solenoid is caused to be actuated by thepresence of a genuine coin in said primary work circuit around saidgalcircuit, thereby to maintain current through said work circuit aroundsaid galvanometer contacts directly to said solenoid from said mainsource of electricity, a normally closed switch in said work circuit andmeans for actuating the same proiecting into said coin chute beyond saidselector for causing said normally closed switch to be opened by thepassage of a genuine coin past said selector, said means being spacedfrom said coin selector a distance relative to the diameter 0! a genuinecoin oi the type for which the device is designed to be actuated andsaid distance being substantially-less than the distance between saidpair of coin contacts and said coin selector, whereby the interruptionoi current to said solenoid will be insured by the passage of a genuinecoin past said selector before a second coin can travel in said coinchute past said selector.

4. In a coin-detecting device, a coin chute, a

coin selector in said coin chute, a circuit controlling the energizationof said coin selector, a pair of spaced contacts in said coin chute andconnected in said circuit adapted when bridged by a genuine coin throughsaid circuit, a normally closed switch in said circuit and resilientmeans for actuating said switch located to the entrance of said coinchute and adjacent to said pair of contacts adapted to yield to permitthe insertion of a coin into said chute to engage said contacts and whenengaged by a coin withdrawn irons said coin chute to open said switch.

JAMES F. sacrum. wnnnnmi R. BROOKS.

